A tire air pressure monitoring system that functions as a tire valve ID registration system is known in the art. The tire valve ID registration system automatically registers the ID of a tire valve (valve ID) to a receiver as the ID of a tire of an associated vehicle without using a trigger generation device such as an initiator. (e.g., refer to patent document 1). By eliminating the need for an initiator to register the valve ID to the receiver, the number of components installed in the vehicle may be reduced.